Do shifters have internal limit thingymagigs?

homers_double

Hard to explain so bear with me please... out on a ride this morning and all of a sudden there was a clunk from somewhere on the front shifter/mech. Then the derailleur threw the chain off the big ring.

Nothing around the mech seems to have moved but now it goes right past the big ring on every shift.

Also, when pressing the down shift paddle it clicks a bit when pressed even when it's at its lowest point and can't shift any lower, would anyone with Tigara shifters be kind enough to see if they get the same click, I can't recall it being like that before and the rear shifter doesn't do it.

I'm thinking that something to do with the indexing in the shifter has given up but it's an odd one and I have no experience with road shifters, only Mtb.



Cheers.

chris_bass

seems weird that if something has gone wrong that it would go off the big ring, that would need more tension in teh cable.

Might be along shot but the limit screw hasn't come out or sheered off has it? so it allows the mech to move further out?

Schobiedoo

Limit screws on the derailleur control the lower and upper limit of movement. The levers pull the correct amount of cable through the system to move the derailleur the correct amount to shift (the barrel adjusters tweak this amount). If it's throwing the chain off the ring, then the limit screws should be the culprit unless something has broken, and would also cause the indexing to go awry.

Start by unclamping the cable from the derailleur, (re)set the limit screws on lower and upper, reconnect the cable and then index the gears with the barrel adjusters.